JavaStation Client Software Guide

The DHCP Service Configuration Table

The DHCP Service Configuration Table contains groups of DHCP options that are delivered to DHCP clients. For a complete description of this table, refer to the dhcptab(4) man page. Throughout this section this table will be called the dhcptab file.

The DHCP options that can be delivered to JavaStation computers are a subset of all the options supported by the DHCP specification. Some DHCP options are required for a successful JavaStation boot; others are optional.

Required DHCP Options

The following table lists the DHCP options required in dhcptab to boot JavaStation computers. The left column gives the option number as defined in the DHCP specification (RFC 2132), if it exists. The middle column gives the symbol name for the option in the Solaris implementation of DHCP (the name used in dhcptab). See "Sample dhcptab File " to see how these names are used.

Table 2-3 DHCP Options Required to Boot JavaStation Computers

DHCP Option Name (Number) 

Symbol Name in Solaris dhcptab File


N/A (This symbol is a DHCP field, not an option.) 


The IP address of the server with the initial boot file (either the booter or the JavaOS image). See Table 2-6 for more information.

IP Address Lease Time (51)  


The duration (in seconds) of the IP address lease. A value of -1 indicates an infinite lease. After this period of time has expired without being renewed, the JavaOS software shuts down the networking port.

Subnet Mask (1)  


The subnet mask. 

Domain Name Server (6)  


The IP addresses of one or more DNS servers. The JavaOS software queries additional DNS servers if the primary server fails to respond.  

DNS Domain Name (40)  


The DNS domain name. 

Root Path (17)  


The NFS-exported directory containing the JavaOS image. This option is used by the booter to locate the JavaOS binary and by the JavaOS software to locate a newer image to update the flash. This option is required if you are using the booter method or if flash update is enabled. See Table 2-6 for more information.

The options DHCP Message Type (53) and Server Identifier (54) are also required in every DHCP packet. However, these options are provided automatically by the DHCP server and do not need to be specified in dhcptab.

Optional DHCP Options

The following table lists the DHCP options that can be interpreted by the DHCP client during the JavaStation boot sequence but are not necessarily required for the boot sequence.

Table 2-4 Optional DHCP Options for Booting JavaStation Computers

DHCP Option Name (Number)  

Symbol Name in Solaris dhcptab File


Bootfile Name (67)  


The path name of the initial boot file, which can be a "booter" file or the JavaOS software. The path name is assumed to be relative to the TFTP root directory.  

If this option is not provided, the name of the booter is assumed to be the same as the Client Class Identifier (SUNW.JDM1 for a brick model; SUNW.JSIIep for a tower model) and is assumed to be in the TFTP root directory. See Table 2-6 for more information.

Broadcast Address (28)  


The network broadcast address.  

Router (3) 


The IP address of the router to be used by the JavaStation clients. If not given, the JavaOS software uses router discovery to locate a router.  

Time Server (4)  


The IP address of a server supporting the RFC 868 time protocol.  

N/A (Solaris-specific flag) 


A boolean flag which by its presence tells the DHCP server to renew the leases of clients requesting IP address lease renewal.  

NIS Servers (41) 


If the IP address of an NIS server is not given, the JavaOS software broadcasts looking for NIS servers. (This works only if the NIS server is on the same subnet.) 

NIS Domain Name (40) 


The NIS domain name. 

Vendor-Specific Options (43) 

Symbol names are defined by the user. By convention, use JOScmd1 through JOScmd4,

JOSchksm, and JSBproto

A list of vendor-specific options. See "Vendor-Specific Options".

See "Sample dhcptab File " for examples of how these options are set in dhcptab.

Vendor-Specific Options

The DHCP specification enables hardware and software vendors to create their own DHCP options. These options are delivered through the use of the Client Class Identifier option and the Vendor-Specific Options option. If a DHCP client identifies itself as being of a certain class of client, and the DHCP server has been configured to serve that class of clients, then the DHCP server can respond with a set of options specific to that client type.

Vendor-Specific Options can be used to deliver the JavaOS checksum, JavaOS property settings, and the JavaOS boot protocol to the JavaStation computer during the boot sequence.

The delivery of Vendor-Specific Options to JavaStation clients works as follows. The DHCP client on the JavaStation (the PROM or the JavaOS software) includes the JavaStation hardware's Client Class Identifier (DHCP Option #60) in every packet sent to the DHCP server. When the DHCP server receives the Client Class Identifier, it will deliver the JavaOS checksum, boot protocol, and/or property settings in the Vendor-Specific Options if it has been configured to do so.

The JavaStation hardware's Client Class Identifier is specified in the PROM. The table below lists the Client Class Identifiers for each JavaStation model.

Table 2-5 JavaStation Client Class Identifiers

JavaStation Model 

Client Class Identifier 

Brick model 


Tower model 


Examine the sample dhcptab file below for examples of setting the JavaOS checksum and JavaOS properties in dhcptab. Note, however, that JavaOS properties can be delivered to the JavaOS software using methods other than the DHCP Vendor-Specific Options. See Chapter 4, JavaOS Properties for more information.

Sample dhcptab File

The following sample dhcptab file supplies DHCP options to a variety of clients on a network. Some options are common to all clients. Other options are specific to clients attached to the server, to classes of JavaStation clients, or to specific JavaStation machines. Note that dhcptab can serve many different clients, not just JavaStation computers.

# /var/dhcp/dhcptab
# This file is a sample DHCP server configuration database for 
# JavaStation clients.
# Refer to dhcptab(4) for details. This table is generated by
# using the dhcpconfig(1M) command in conjunction with the
# dhtadm(1M) command. It can be administered with the dhtadm
# command.

# The following are symbol definitions for the Vendor-Specific 
# Options. Symbol definitions are used to create dhcptab macros.
# Refer to the dhcptab(4) man page for symbol definition syntax and
# instructions on creating macros. 

# JOScmd1-4 are for JavaOS properties, JOSchksm is for the 
# JavaOS checksum, and JSBproto is for the JavaOS boot protocol. 

JOScmd1				s		Vendor=SUNW.JSIIep SUNW.JDM1,101,ASCII,1,0
JOScmd2				s 		Vendor=SUNW.JSIIep SUNW.JDM1,102,ASCII,1,0
JOScmd3				s 		Vendor=SUNW.JSIIep SUNW.JDM1,103,ASCII,1,0
JOScmd4				s 		Vendor=SUNW.JSIIep SUNW.JDM1,104,ASCII,1,0

JOSchksm 				s 		Vendor=SUNW.JSIIep,128,NUMBER,4,1

JSBproto				s		Vendor=SUNW.JSIIep,129,ASCII,1,0

# Standard macros generated when configured with dhcpconfig(1M). # The first is the time offset from GMT (UTC) time, the second
# applies to all clients serviced by this server, and the third
# applies to all clients attached to one of the nets attached to
# the server.

Locale			m 	:UTCoffst=-25200:

gibson			m 	:Include=Locale:Timeserv=\
				:DNSserv=\						m 		:Broadcst=\

# These are macros used to configure specific classes of clients. 
# In this case the JavaStation tower and brick models respectively.

SUNW.JSIIep						m 		:Rootpath="/export/root/javaos/JSIIep":\

SUNW.JDM1				m 			:Rootpath="/export/root/javaos/JDM1":\

# The macros below contain individual DHCP options for the two
# JavaStation computers whose client ID's (derived from the
# Ethernet address) match the keys. Here each JavaStation gets 
# its boot image from a boot server other than the DHCP server. 
# The first JavaStation uses NFS to directly download the 
# JavaOS image. The second JavaStation computer gets a different
# properties file as well as empty vendor options that override
# any previous default definitions.

0800208E0668						m 			:BootSrvA=\

08002087BED4						m 			:BootSrvA=\